Cisco Headend System Release 2.5 Release Notes
4001159 Rev B
Why Choose System Release 3.5?
1-3
DSG: New DOCSIS Option Can Consolidate Administration of the Data
Network
Overview
Existing support for DOCSIS-capable set-tops is enhanced with the introduction of
DOCSIS mode and single-flow multicast. This chapter describes new network
configurations and several UI changes associated with these new features.
Use One IP Address and Less Bandwidth with Single-flow Multicast
Previous system releases relied solely on unicast internet protocol (IP) routing to
deliver Broadcast File System (BFS) and broadcast data, system information (SI),
conditional access information, and PassThru messages to different set-top
populations. With unicast IP routing, the DNCS can only send data to one
destination at a time. Because unicast traffic is destined for a unique IP address,
network administrators must configure a different OOB bridge on the DNCS for
each physical OOB bridge on the network. Each physical bridge consumes
additional network bandwidth for each additional OOB bridge.
For a given hub with unicast IP routing, the destination IP address for each OOB
For a given hub with unicast IP routing, the destination IP address for each OOB
bridge is unique; however, the information carried across each bridge is almost
exactly the same. The following diagram provides a basic example of unicast IP
routing in a single hub. In this example, each OOB bridge requires 0.3 Mbps of
bandwidth. The network uses four different IP addresses and a total of 1.2 Mbps of
bandwidth to deliver four copies of the same data to multiple set-top populations.